Time step about forced harmonic simulation

chunlong Tan · September 19, 2022, 10:01

Dear all,

when I chosen Harmonic->Fluid Structure->Mechanical Coupling->Modal->Forced motion to conduct an flutter analysis. I found that there was no imformation about iteration time step. I'm wondering if this type of simulation is not related to the time step, or if I didn't find where to set the time step.

Kind regards,
Chunlong

Wout Poncelet · September 30, 2022, 11:43

Dear Chunlong,

Given that you're performing a flutter analysis and you mention the harmonic, I assume you're running a NLH simulation? Is my understanding correct?

In that case, there is no need to specify a time step (just a CFL number). The NLH method will solve the NS-equations in the frequency domain. Once your simulation is converged, you will be able to reconstruct your solution in space and time, here you can specify the time step and the number of time steps you want to reconstruct.

The imposed forced motion, in case of a NLH simulation, can be constant in time or defined with a given frequency/mean value/IBPA/Real and imaginary part.

I hope this may help you.

With best regards,
Wout Poncelet

chunlong Tan · October 13, 2022, 03:22

Dear Wout,

Thank you, your answer has completely solved my confusion.

Kind regards,
Chunlong

September 19, 2022, 10:01	Time step about forced harmonic simulation	#1
chunlong Tan New Member chunlong Tan Join Date: Sep 2022 Posts: 8 Rep Power: 4	Dear all, when I chosen Harmonic->Fluid Structure->Mechanical Coupling->Modal->Forced motion to conduct an flutter analysis. I found that there was no imformation about iteration time step. I'm wondering if this type of simulation is not related to the time step, or if I didn't find where to set the time step. Kind regards, Chunlong

September 30, 2022, 11:43	Time step about forced harmonic simulation	#2
Wout Poncelet New Member Wout Poncelet Join Date: Sep 2022 Posts: 1 Rep Power: 0	Dear Chunlong, Given that you're performing a flutter analysis and you mention the harmonic, I assume you're running a NLH simulation? Is my understanding correct? In that case, there is no need to specify a time step (just a CFL number). The NLH method will solve the NS-equations in the frequency domain. Once your simulation is converged, you will be able to reconstruct your solution in space and time, here you can specify the time step and the number of time steps you want to reconstruct. The imposed forced motion, in case of a NLH simulation, can be constant in time or defined with a given frequency/mean value/IBPA/Real and imaginary part. I hope this may help you. With best regards, Wout Poncelet colinda1 likes this.

October 13, 2022, 03:22	Time step about forced harmonic simulationReply to Thread	#3
chunlong Tan New Member chunlong Tan Join Date: Sep 2022 Posts: 8 Rep Power: 4	Dear Wout, Thank you, your answer has completely solved my confusion. Kind regards, Chunlong colinda1 likes this.

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